Is there a way to get disc on the front of my 64 jetstar 88. The 9" brakes arent very good.

 

Is this at all possible?

 

This swap is hard for 65-70 big cars. In that era they started with 4 wheel drums with single master and transitioned to front disc/rear drums by 69/70.

64 to 65 was a generational change probably making this particular swap yet harder. It’s made yet harder since you have a J88. It may have A-body brakes with the 330 as a combo cost play from factory. If so, see what you can find about swaps to discs for a ‘64 Cutlass. There are a ton, ton of A-body brake upgrade solutions. Maybe even 4 wheel discs for high $. Your question is whether there is a subset of that universe which will fit your B-body “big” car. Since the J88 is actually a “big car” the A-body-upgrade approach may fail.

If A body parts fail, I can think of a couple more options:

1) See if the J88 and Delta 88 ball joints from ‘64 to 65 swap, then you can consider swapping in a pair of 67-70 disc brake spindles and related rotors/calipers, etc. from the late 60’s. In ‘71 everything changed, consider 1970 your swap year limit. The key here will be ball joint diameter & taper. If they happen to be the same from 64 J88 to to say, a 69 88/98, you’re on your way.

2) Go custom. Find a brake professional, likely 55-65 years of age or older who can recommend a swap recipe. Computers and online sources won’t tell the tale. Expect this to be a game of micrometer measurements and iterating (at cost to you) until you get to something that works.

3) Scarebird. See posts on this site about their offerings. I believe the trade off is possible availability at the cost of smaller than (big car) stock discs.

4) See if you can overall upgrade to a 69 or 70 era set of disc/drum brakes to increase the brake swept area beyond what Olds provided for J88’s in 1964.

I’ve added disc brakes to both of my ‘66 big cars. One has stock rotors and calipers from ‘70, the other has slightly tweaks latter day caddy rotors modified to fit ‘69 Olds disc brake spindles and bearings.

On the big cars, please know that the drum brake spindles are different from disc brake spindles, but it may be possible to grind the drum brake spindle circular pad down just a bit to become a disk brake spindle. I have not done this, I went with from-the-factory disc spindles, but saw that the difference was a 1/4” to 3/8” on a circular pad where the drum spindles were proud of the disc spindles. I surmise, but have not tested, that you could grind down 65-70 drum spindles to work with discs. All of that, assuming 64 to latter day spindles can swap. I can not offer any view on that.

You’re aiming at something smart which will protect you & your passengers over time. This worth doing at least as well as a powerful motor on safety grounds. In 2023, everything you’re driving around stops better than a J88 with small brakes from 59 years ago. Until you do a swap, leave a helluva a lot of room between you & the car in front of you. The unfun part will be all the jerks who cut into your lane in traffic forcing you to back off further still.

The fun part will be they’re commuting in their disposable econoboxes. You’re enjoying your 59 year old Olds.

Hope this helps you,
Chris

 

Thank you. And yes i have multiple passengers my 3 kids. Was hopibg soneone had done the swap already. I searched the forum but i cant find info on it working. Mostly just that 64 j88 cars have there own spindles. Can i switch to 64 starfire setup or something else than a j88 i think that will get you 11" drums

 

Upfront, I’m just a hobbyist, not a pro and my real knowledge begins with 65 cars since I’ve never had a 64. You’ve got a good idea in upgrading to full size brakes on your J88.

I you want to go after upgrading to 1964 big car brakes, you’ll need to find a donor car, either a 88, Starfire or 98 from 64 to start, though as you research that generation of Olds, you may find that 63 or 62 parts or maybe even ‘65 parts may swap in.

You’re aiming at the lowest mileage car you can find. When you’re in the junkyard, or buying a donor car, know the minimum drum thickness spec and take a device to measure the drums on the donor to confirm or deny that they have a enough meat left to be used on your car. Cars of this age have sometimes, maybe often turned over the 100,000 mile mark once or more.

I’d start with grabbing everything bolts to the frame. - A arms, spindles, backing plates, etc in front, and if you have room to store it, the whole rear axle with the bigger brakes. If not the whole rear, get the axles, backing plates drums and shoes for the rear.

When you go through the brakes replace the rubber hoses with new and inspect the steel lines to confirm or deny that they will work reliably on your car.

The other major upgrade I’d recommend would be a dual circuit drum master cylinder from 1967 or later. Up to 1966 Olds used a single circuit master which means if you blow a brake line or hose you lose 100% of your brakes. The feds changed this in ‘67 a safety regulation and forced the manufacturers to go with 2 circuits which means that even if you blow a hose you still have 50% of your brakes.

Overall know that restoring 60’s Olds big cars is a tougher game than your averagel Mustang or Camaro. The restoration market is small, so there’s not much aftermarket support. This forces us to head for the specialty junkyards which have kept these cars to part out for the last 30-50+ years. It also forces us to get creative with parts swapping to keep these cars on the road. The reason I mention a donor car is that if you need brakes, you may eventually need A-arms, driveshaft, engine parts, electrical harnesses, glass and so on, in some cases getting a dead donor can be cheaper than a few parts at a time - assuming you have space to store & strip a donor.

Some Cutlass stuff swaps into the big cars, but generally the big cars were a different, somewhat heavier duty animal owing mostly to weight/size differences. Ask around about old-car boneyards in your area and look at places like Desert Valley Auto (DVAP) in AZ, French Lake Auto Parts in MN, Turners in Fresno, CA, Hess Brothers in Red Bluff CA, etc.

Also post a parts request here on CO, there are helpful people here who just might have the parts you need.

Cheers
cf

 

This isn't going to work. Not only are the spindles different from 63-64 to 65-70, but the J88 spindles are one-year-only, one-model-only. Keep in mind that the J88 used the A-body 9.5" drum brakes and the 5x4.75" wheel bolt pattern.

The interesting thing here is that the J88 DOES use the same wheel bearings and hubs as do the A-body cars. That means that you can physically install an A-body rotor onto a J88 spindle. I do not know if it will actually clear the bosses or steering arms, however. Once you do that, you can modify the A-body caliper brackets to bolt to the J88 spindles by welding tabs onto them and drilling new holes. Similar to the difference between the drum and disk spindles on the A-body cars, you may need to mill down the backing plate mounting boss on the J88 spindles.

Of course, simply bolting up disc brakes is the easy part. Getting proper front/rear brake balance is where the skill comes in. Heck, most aftermarket disc brake providers don't even understand this. GM used a wide range of proportioning valves to achieve the correct brake balance while accounting for vehicle weight, front/back weight distribution, and tire compound and size. Note that tires affect braking just as much as the actual brake hardware. All aftermarket kits include the one-size-fits-none Chinesium combination valve that almost certainly is not properly calibrated for the application. But I'm sure that after spending all that time and money on a disc brake conversion, one will swear that the car stops better (usually because the old drum brakes were not properly maintained or adjusted).

 

I know theres a lot to it. And i hardly know enough to scratch the surface. I believe the diameter of the caliper pistons need to match the master cylinder as well for distribution. I can handle machining brackets an calipers no issue.

 

The diameter of the master cylinder piston and the caliper/wheel cylinder pistons all effect brake force. Master cylinder piston diameter sets hydraulic line pressure for a given foot pressure on the pedal. Diameter of the pistons at the wheels sets the clamping force at the wheel. The resulting braking torque on the wheel is a function of this clamping force plus the diameter of the rotor or drum. How this then translates to stopping depends on the tire diameter, compound, and road surface. Suffice to say that there are a LOT of variables. On my 62 F85, I was able to significantly improve braking force of the stock four wheel drums by changing from the OEM 1" master cylinder to a 7/8" M/C, which increased line pressure for a given pedal pressure.

 

Now that you have Joe P on the case, I’ll sit back & learn.

I did not know the J88 spindles were so unusual.

Good luck with your upgrade, these cars are much more fun when they’re safe & reliable.

Chris

 

I had a '64 Jetstar 88 from 1991 to 1996, and I never felt the brakes were inadequate. I did completely redo the hardware both front and rear when I got the car.

People hear that this car used the Cutlass brake hardware and assume that the brakes will be inferior, so they get psyched into feeling it when they drive the car. Front drums are inferior to front discs in principle, but that doesn't mean that front drums didn't work. Cars were equipped this way for decades leading up to the conversion to front discs in the early '70s.

As Joe P. says, make sure what you have is in good working order and properly adjusted. Switching over to front discs could create more problems than you solve. I get a headache just reading through everything you would need to do, drilling here, milling there, ad infinitum. Think how much easier it would be to just leave what's on the car there and use the brakes it was born with and was designed to use.

Oldsmobile built well over 100,000 Jetstar 88s from 1964 to 1966. All those cars can't be wrong

 

As equipped from the factory, the Jetstar 88 was neither unsafe nor unreliable.